1. Field of Invention
The present invention relates to a motor pump for supplying and discharging fluid such as water and the like.
2. Description of Related Art
In general, many motor pumps have a pump unit mounted to the extreme end of a motor shaft projecting from a motor casing through a seal member. Some motor pumps employ a so-called "brushless electric motor" having a stator coil disposed at an inner periphery of a motor casing as a motor unit. Conventionally, this type of motor pump has a motor unit as shown in FIG. 3 that includes a motor shaft 17 projecting from a motor casing 16 as well as an accommodation chamber 19. A controller 18 for controlling a magnetic field of the stator coil is disposed within the accommodation chamber 19 that is located in a base end of the motor casing 16. For simplicity of illustration, the pump unit is not mounted to an end of the motor shaft 17 in FIG. 3.
Since the conventional motor pump must cope with heat generated by the controller 18, the motor pump must cool the controller 18 by having a large radiation fin 19a formed in the accommodation chamber 19. However, since the accommodation chamber 19 requires space for forming the radiation fin 19a in addition to an intrinsically necessary space required for this arrangement, this design prevents the reduction of weight and size of the motor pump. Further, when the radiation fin 19a is intended to dissipate heat generated by the motor unit, the size of the motor pump is further increased. Thus, there is a problem associated with reduction of weight and size of the motor pump when the radiation fin 19a is used to cool, i.e. dissipate heat, generated by the controller 18 and/or the motor unit. The present invention resolves this problem.